Airbag sensor attachment structure

ABSTRACT

A vehicle body front section structure is provided with a sensor attachment structure to an outside face of a left bumper beam extension. The sensor attachment structure includes a support section provided on the outside face of the left bumper beam extension, and an airbag sensor attached to the support section. The support section deforms and retreats toward the vehicle body rear as a result of compression of the left bumper beam extension during compression of the left bumper beam extension due to an impact load input from the vehicle body front.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to JapanesePatent Application No. 2016-031158, filed Feb. 22, 2016, entitled“Airbag Sensor Attachment Structure.” The contents of this applicationare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to an airbag sensor attachment structurethat is provided on a bumper beam extension at a front end of a frontside frame and that attaches an airbag sensor to the bumper beamextension.

BACKGROUND

In a known airbag sensor attachment structure, a crash box (referred tobelow as a “bumper beam extension”) is provided at a front end portionof a front side frame, and an airbag sensor is attached to a front wallof the bumper beam extension inside the bumper beam extension (forexample, see Japanese Unexamined Patent Application Publication No.5-112195).

In the airbag sensor attachment structure in Japanese Unexamined PatentApplication Publication No. 5-112195, the airbag sensor is housed insidethe bumper beam extension, thereby enabling working space to be securedfor assembly of a bumper beam or the like to a front end portion of thefront side frame.

Moreover, in a full overlap frontal collision or an offset collision,for example, the bumper beam extension undergoes compression (namely,axial crushing), and the airbag sensor moves toward the vehicle bodyrear. This enables detection of the full overlap frontal collision orthe offset collision by the airbag sensor.

However, in the airbag sensor attachment structure in JapaneseUnexamined Patent Application Publication No. 5-112195, the airbagsensor is housed inside the bumper beam extension. Accordingly, the fulloverlap frontal collision or offset collision cannot be detected by theairbag sensor until the bumper beam extension has been compressed. It istherefore difficult for the airbag sensor to detect a collision at anearly stage, during an initial stage of a full overlap frontal collisionor offset collision.

In another known airbag sensor attachment structure, a flange of abumper beam extension is provided to a flange at a front end portion ofa front side frame, and an airbag sensor is attached to the flange ofthe bumper beam extension (see, for example, Japanese Patent No.3690232).

In the airbag sensor attachment structure of Japanese Patent No.3690232, in a full overlap frontal collision or an offset collision, forexample, the bumper beam extension is compressed, enabling detection ofthe full overlap frontal collision or the offset collision by the airbagsensor.

However, in the airbag sensor attachment structure of Japanese PatentNo. 3690232, the airbag sensor is attached to the flange of the bumperbeam extension (namely, a base portion of the bumper beam extension). Itis accordingly difficult for the airbag sensor to detect a collision atan early stage during an initial stage of a full overlap frontalcollision or offset collision.

SUMMARY

A conceivable countermeasure to this issue would be to provide a bracketextending forward from the flange toward the vehicle body front, as faras a front wall of the bumper beam extension, and to attach the airbagsensor to the bracket.

However, if a bracket were to be extended from the flange as far as thefront wall of the bumper beam extension, the bracket would have a largelength dimension. Since the airbag sensor would be supported in acantilevered state at a leading end portion of the bracket, the airbagsensor would be susceptible to vibration during vehicle travel, leadingto the possibility of detection not being possible, or of makingerroneous detection.

Moreover, a bracket with a long length dimension would be required inorder to support the airbag sensor, leading to an increase in componentsand an increase in weight.

The present disclosure provides, for example, an airbag sensorattachment structure capable of detecting a collision precisely and atan early stage using an airbag sensor.

A first aspect of the disclosure describes an airbag sensor attachmentstructure for attachment to a vehicle body front section structureincluding a front side frame extending in a vehicle body front-reardirection and a bumper beam extension extending out from a front end ofthe front side frame toward the vehicle body front at both front sidesections of a vehicle body, and a bumper beam provided at a front end ofthe bumper beam extensions. The airbag sensor attachment structureincludes: a support section that is provided at an external face of thebumper beam extension, and that retreats toward the vehicle body rearaccompanying compression of the bumper beam extension during compressionof the bumper beam extension due to an impact load input from thevehicle body front; and an airbag sensor that is attached to the supportsection.

As described above, the support section is provided on the external faceof the bumper beam extension, and the airbag sensor (namely, a frontalcollision sensor) is attached to the support section.

Note that in a light collision in a low speed range in which it is notnecessary to deploy an airbag (namely, light frontal collisions), thebumper beam undergoes bending and crushing defamation to absorb impactload. On the other hand, the bumper beam extension has strength andrigidity against light collisions, and there is little compression(namely, axial crushing) of the bumper beam extension.

Accordingly, in a light collision, movement of the airbag sensor towardthe vehicle body rear is suppressed, enabling the airbag sensor to beprevented from detecting a light collision unnecessarily and deployingthe airbag.

Moreover, for example, in an offset collision at a lower limit of thespeed for actuating the airbag (specifically, in an intermediate speedrange), the front end of the bumper beam extension intrudes into acomparatively soft material part of a frontmost section of a counterpartvehicle in an initial stage of the collision. The comparatively softmaterial part of the counterpart vehicle impinges on the support sectionsuch that the support section retreats toward the vehicle body rear.

Accordingly, the airbag sensor retreats toward the vehicle body reartogether with the support section, enabling collision informationrequired for airbag deployment to be detected precisely and at an earlystage by the airbag sensor. This thereby enables the airbag to bedeployed in an initial stage of the offset collision.

Note that an offset collision is a collision in which part of the frontsection of the vehicle (approximately half of the width of the front ofthe vehicle body) collides with an obstacle such as another vehicle.

Moreover, for example, in a full overlap frontal collision in a highspeed range (referred to below as a high speed frontal collision), or ina small overlap collision, sufficient to fully crush the bumper beamextension over its entire range, the bumper beam extension can undergocompression (namely, axial crushing) due to the impact load input fromthe vehicle body front. When this occurs, the support section can bemade to retreat toward the vehicle body rear due to compression of thebumper beam extension.

The airbag sensor can accordingly be made to retreat toward the vehiclebody rear together with the support section. This thereby enablescollision information to be detected precisely and at an early stage bythe airbag sensor in a high speed frontal collision or a small overlapcollision.

In a second aspect of the disclosure, configuration may preferably bemade in which the support section includes: a stay that includes a frontjoining portion and a rear joining portion provided on the external faceof the bumper beam extension, and that is famed in a substantiallyhat-shape in plan view; and a bracket that includes an attachment baseportion provided to the stay at an apex portion of the stay separatedfrom the external face of the bumper beam extension, and a projectingportion projecting out from the attachment base portion and to which theairbag sensor is attached. The bracket is formed in a substantiallyL-shape in plan view by the attachment base portion and the projectingportion.

As described above, the stay of the support section is famed in asubstantially hat-shape in plan view. The front joining portion and therear joining portion of the stay are provided on the external face ofthe bumper beam extension. The strength and rigidity of the stay canaccordingly be raised. Moreover, since the stay is famed in asubstantially hat-shape in plan view, the apex portion of the stay canbe separated from the external face of the bumper beam extension.

The attachment base portion of the bracket is provided to the apexportion of the stay, and the projecting portion projects out from theattachment base portion. This thereby enables a projection amount(extension amount) of the projecting portion to be kept small. Theairbag sensor is attached to the projecting portion that has a smallprojection amount.

Accordingly, the characteristic vibration value (resonance frequency) ofthe support section can be raised in a state in which the airbag sensoris supported by the support section, enabling the anti-noise performance(anti-vibration performance) of the airbag sensor to be improved. Thisthereby enables the collision information required for airbag deploymentto be detected precisely and at an early stage by the airbag sensor.

In a third aspect of the disclosure, configuration may preferably bemade in which the bracket is famed from sheet steel.

Note that it is conceivable that the bracket (namely, the projectingportion) could hit a counterpart vehicle in an offset collision. Thebracket is therefore famed from sheet steel. This thereby enables abending state of the projecting portion with respect to impact loadinput to the projecting portion to be regulated (controlled) easily whenthe projecting portion of the bracket hits the counterpart vehicle.

In a fourth aspect of the disclosure, configuration may preferably bemade in which the bumper beam extension and the stay are formed from analuminum alloy. The bracket is fastened to the stay by a fasteningmember; and the fastening member is coated against galvanic corrosion.

As described above, the bumper beam extension and the stay are formedfrom an aluminum alloy, and the fastening member (such as a bolt orrivet) is coated against galvanic corrosion. The steel bracket isfastened to the stay by the fastening member. Galvanic corrosion betweenthe stay and the fastening member can accordingly be suppressed,enabling the durability of the stay and the fastening member to beraised.

In a fifth aspect of the disclosure, configuration may preferably bemade in which the bumper beam is formed with a hollow cross-section, anda rear portion at both end portions of the bumper beam is fixed to afront end of the bumper beam extension. The bumper beam extension issecured with strength and rigidity against a light collision.

As described above, the bumper beam is famed with a hollow crosssection, and the rear portion at both end portions of the bumper beam isfixed to the front end of the bumper beam extension. Moreover, thestrength and rigidity of the bumper beam extension are secured againstlight collisions (namely, in a low speed range in which it is notnecessary to deploy an airbag). The bumper beam thereby undergoesbending and crushing deformation to absorb impact load in a lightcollision.

On the other hand, compression (namely, axial crushing) of the bumperbeam extension is suppressed, enabling movement of the airbag sensortoward the vehicle body rear to be suppressed. This thereby enables theairbag sensor to be prevented from detecting a light collisionunnecessarily and deploying the airbag.

In a sixth aspect of the disclosure, configuration may preferably bemade in which the bumper beam is formed with a hollow cross-section, anda rear portion at both end portions of the bumper beam is fixed to afront end of the bumper beam extension. The bumper beam extension issecured with rigidity against a light collision, and the front joiningportion and the rear joining portion of the stay are provided on theexternal face of the bumper beam extension at a spacing between eachother in the vehicle body front-rear direction.

As described above, the bumper beam is famed with a hollow crosssection, and the rear portion at both end portions of the bumper beam isfixed to the front end of the bumper beam extension. Moreover, thestrength and rigidity of the bumper beam extension are secured against alight collision (namely, in the low speed range in which it is notnecessary to deploy the airbag). The bumper beam thereby undergoesbending and crushing defamation to absorb impact load in a lightcollision.

On the other hand, compression (namely, axial crushing) of the bumperbeam extension is suppressed, enabling movement of the airbag sensortoward the vehicle body rear to be suppressed. This thereby enables theairbag sensor to be prevented from detecting a light collisionunnecessarily and deploying the airbag.

Moreover, the front joining portion and the rear joining portion of thestay are provided on the external face of the bumper beam extension at aspacing between each other in the vehicle body front-rear direction.Namely, the strength and rigidity of the stay in the direction in whichthe bumper beam extension is compressed are kept appropriately low. Thisthereby enables the front joining portion of the stay to move toward thevehicle body rear during compression of the bumper beam extension towardthe vehicle body rear due to a high speed frontal collision sufficientto fully crush the bumper beam extension over its entire range.

Accordingly, the bumper beam extension can be stably compressed towardthe vehicle body rear, and the front side frame can be stably defamed,without compression (crushing defamation) of the bumper beam extensionbeing obstructed by the stay. This thereby enables the airbag sensor tobe made to retreat toward the vehicle body rear accompanying compressionof the bumper beam extension, and enables collision information to bedetected precisely and at an early stage by the airbag sensor.

In a seventh aspect of the disclosure, configuration may preferably bemade in which the bracket includes: a flange that is formed at an upperend or a lower end of the bracket so as to be continuous to theattachment base portion, the projecting portion, and a bend portionwhere the attachment base portion and the projecting portion intersect;and a connector protector that protrudes out from the upper end or thelower end of the bracket.

As described above, the flange is formed at the upper end or the lowerend of the bracket. The strength and rigidity of the bracket canaccordingly be raised by the flange. This thereby enables thecharacteristic resonance value of the bracket to be raised, enabling theanti-noise performance (anti-vibration performance) of the airbag sensorto be improved.

Moreover, the connector protector protrudes out from the upper end orthe lower end of the bracket. This thereby enables a wire harness of theairbag sensor to be protected by the connector protector, even when theairbag sensor is provided in a range intruded into by a collidingobject. This thereby enables the cutting of the connection of the wireharness to the airbag sensor to be prevented.

In an eighth aspect of the disclosure, configuration may preferably bemade in which the airbag sensors are respectively attached to the bumperbeam extension on a left side of the vehicle body and to the bumper beamextension on a right side of the vehicle body; and the left side airbagsensor and the right side airbag sensor are inclined such that adistance from the left side airbag sensor to a vehicle body center, anda distance from the right side airbag sensor to the vehicle body center,are the same as each other.

In this manner, the left side airbag sensor and the right side airbagsensor can be configured using common components, thereby enabling coststo be suppressed.

Moreover, the left side airbag sensor and the right side airbag sensorare inclined. Accordingly, the wire harnesses connected to therespective airbag sensors can be brought closer to the side of therespective stays. This thereby enables the connector protectors to bebrought closer to the side of the respective stays, enabling thecharacteristic vibration values of the respective support sections to beraised. Accordingly, resonance of the airbag sensors is suppressed,thereby enabling erroneous detection by the airbag sensors to beprevented.

Moreover, the height of the respective airbag sensors can be kept lowdue to inclining the left side airbag sensor and the right side airbagsensor. This thereby enables spaces to be secured above the respectiveairbag sensors. This enables an increase in the degree of freedom in thelayout when placing surrounding components (headlights, cooling pipes,and small lights such as fog lamps). This moreover enables any effect onthe performance of the surrounding components to be kept small.

Moreover, the distance from each airbag sensor to the vehicle bodycenter is made the same by inclining the left side airbag sensor and theright side airbag sensor. This thereby enables a discrepancy indetection between the left side airbag sensor and the right side airbagsensor to be suppressed from arising in a high speed frontal collision.This thereby enables a collision mode to be accurately determined in ahigh speed frontal collision.

In a ninth aspect of the disclosure, configuration may preferably bemade in which the bumper beam extension has a substantially rectangularshaped external cross-section, has a width dimension famed larger than aheight dimension, and is internally partitioned into plural closedcross-sections.

As described above, the width dimension of the bumper beam extension islarge, and the bumper beam extension is internally partitioned intoplural closed cross-sections (namely, small compartments). The strengthand rigidity of the bumper beam extension can accordingly be raisedappropriately. This thereby enables compression (namely, axial crushing)of the bumper beam extension in a light collision to be suppressed.

However, in a high speed frontal collision sufficient to fully crush thebumper beam extension over its entire range, the bumper beam extensionis capable of undergoing compression (namely, axial crushing) due to theimpact load, enabling the energy absorption amount to be increased.

In a tenth aspect of the disclosure, configuration may preferably bemade further including an upper member provided at a vehicle widthdirection outside of the front side frame, and a coupling section thatcouples a front portion of the upper member and a front portion of thefront side frame together. The bumper beam extension is provided at afront end of the front side frame and at a front end of the couplingsection.

As described above, the front portion of the upper member is coupled tothe front portion of the front side frame by the coupling section.Moreover, the bumper beam extension is provided at the front end of thefront side frame and at the front end of the coupling section.

Accordingly, in a small overlap collision, for example, the impact loadcan be supported by both the front side frame and the upper member. Thebumper beam extension can thus undergo adequate compression (namely,axial crushing) due to the impact load, and the airbag sensor can bemade to retreat toward the vehicle body rear together with the bumperbeam extension. This thereby enables collision information to bedetected precisely and at an early stage by the airbag sensor in a smalloverlap collision.

Note that a small overlap collision is a collision in which a frontsection of the vehicle collides with an obstacle such as a vehicle,tree, or electricity pole at a front side portion at the outside of thefront side frame at ¼ in the vehicle width direction. Note that smalloverlap collisions are also referred to as narrow offset collisions.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the disclosure will become apparent in the followingdescription taken in conjunction with the following drawings.

FIG. 1 is a perspective view illustrating a vehicle body front sectionstructure provided with an airbag sensor attachment structure accordingto an embodiment of the present disclosure.

FIG. 2 is a plan view illustrating the vehicle body front sectionstructure in FIG. 1.

FIG. 3 is an enlarged view of region III in FIG. 1.

FIG. 4 is a view along arrow IV in FIG. 3.

FIG. 5 is a perspective view illustrating a state in which the leftbumper beam extension in FIG. 3 has been cut away along a vehicle widthdirection.

FIG. 6 is a view along arrow VI in FIG. 2.

FIG. 7 is a view along arrow VII in FIG. 3.

FIG. 8 is an exploded perspective view illustrating the airbag sensorattachment structure in FIG. 7.

FIG. 9 is a cross-section taken along line IX-IX in FIG. 1.

FIG. 10A and FIG. 10B are explanatory diagrams to explain an example ofimpact load absorption by a vehicle body front section structureaccording to the embodiment of the present disclosure in a lightcollision.

FIG. 11A and FIG. 11B are explanatory diagrams to explain an example ofearly detection of collision information by an airbag sensor attachmentstructure according to the embodiment of the present disclosure in anoffset collision.

FIG. 12A and FIG. 12B are explanatory diagrams to explain an example ofcompression of a left bumper beam extension according to the embodimentof the present disclosure due to impact load in a high speed frontalcollision.

FIG. 13 is an explanatory diagram to explain an example of earlydetection of collision information by an airbag sensor attachmentstructure according to the embodiment of the present disclosure in ahigh speed frontal collision.

DETAILED DESCRIPTION

Explanation follows regarding a preferred embodiment of the presentdisclosure, with reference to the attached drawings. “Front (Fr)”, “Rear(Rr)”, “Left (L)”, “Right (R)” are directions seen from the perspectiveof a driver.

Embodiment

Explanation follows regarding an airbag sensor attachment structure 20according to an embodiment. The airbag sensor attachment structure 20 isabbreviated to “sensor attachment structure 20” below.

A vehicle body front section structure 10 is configured withsubstantially left-right symmetry. In the following explanation, thesame reference numerals are allocated to configuration members on theleft side and configuration members on the right side. Detailedexplanation is given regarding the configuration members on the leftside, with explanation regarding the configuration members on the rightside being omitted.

As illustrated in FIG. 1 and FIG. 2, the vehicle body front sectionstructure 10 includes a left front side frame (front side frame) 13extending out along the vehicle body front-rear direction from a leftfront side portion 11 a of a vehicle body 11, a left front pillar 14provided at a vehicle width direction outside of the left front sideframe 13, a left upper member (upper member) 15 extending out from theleft front pillar 14 at a downward incline toward the vehicle bodyfront, and a left coupling section (coupling section) 16 that couplesthe left upper member 15 and the left front side frame 13 together.

The vehicle body front section structure 10 further includes a leftbumper beam extension (bumper beam extension) 18 provided to the leftcoupling section 16 and the left front side frame 13, the sensorattachment structure 20 provided to the left bumper beam extension 18,and a bumper beam 22 spanning between respective front ends 18 a of theleft bumper beam extension 18 and a right bumper beam extension (bumperbeam extension) 18.

The left front side frame 13 extends out from beneath the left side of alower dash panel 24 toward the vehicle body front, and is aframework-foaming member of the vehicle body 11. The left front pillar14 is provided on the vehicle width direction outside of the left frontside frame 13. The left upper member 15 extends out from the left frontpillar 14 with a downward incline toward the vehicle body front, so asto approach the left coupling section 16. In this state, the left uppermember 15 is provided on the vehicle width direction outside of the leftfront side frame 13.

As illustrated in FIG. 3 and FIG. 4, a front portion 15 a of the leftupper member 15 is coupled to an outer end portion 16 a of the leftcoupling section 16. Moreover, an inner end portion 16 b of the leftcoupling section 16 is coupled to a front portion 13 a of the left frontside frame 13. Namely, the front portion 13 a of the left front sideframe 13 is coupled to the front portion 15 a of the left upper member15 through the left coupling section 16.

An attachment bracket 23 is provided at a front end 13 b of the leftfront side frame 13, a front end 16 c of the left coupling section 16,and a front end 15 b of the left upper member 15. A rear end 18 b of theleft bumper beam extension 18 is attached to a location 23 a on thevehicle width direction inside of the attachment bracket 23.

Namely, the rear end 18 b of the left bumper beam extension 18 isprovided at the front end 13 b of the left front side frame 13 and thefront end 16 c of the left coupling section 16, such that the attachmentbracket 23 is interposed between the rear end 18 b of the left bumperbeam extension 18 and the front end 13 b of the left front side frame 13and the front end 16 c of the left coupling section 16. In this state,the left bumper beam extension 18 extends out from the front end 13 b ofthe left front side frame 13 and the front end 16 c of the left couplingsection 16 toward the vehicle body front.

As illustrated in FIG. 5, the left bumper beam extension 18 is famedfrom a lightweight metal member such as an aluminum alloy. Specifically,the left bumper beam extension 18 includes a coupling plate 25 attachedto a left attachment member 19, a first shock absorbing member 26attached to the vehicle width direction inside of the coupling plate 25,and a second shock absorbing member 27 attached to the vehicle widthdirection outside of the coupling plate 25.

Namely, the second shock absorbing member 27 is provided at the vehiclewidth direction outside of the first shock absorbing member 26.

The coupling plate 25 is, for example, a member famed by extruding alightweight metal such as an aluminum alloy so as to extend with auniform cross-section profile. The coupling plate 25 can accordingly befamed (namely, manufactured) easily.

The coupling plate 25 is attached to the left attachment member 19 fromthe vehicle body front side using bolts 28 and nuts 29 (see FIG. 4 forthe nuts 29).

The first shock absorbing member 26 is, for example, a member formed byextruding a lightweight metal such as an aluminum alloy so as to extendwith a uniform cross-section profile along the vehicle body front-reardirection. The first shock absorbing member 26 can accordingly be formed(namely, manufactured) easily. A base portion 26 a of the first shockabsorbing member 26 is joined to a vehicle width direction inside half25 a of the coupling plate 25 by MIG welding.

Specifically, the first shock absorbing member 26 includes a firstexternal peripheral wall 31 famed with a substantially rectangularshaped closed cross-section profile, and first partitioning walls 32that internally partition the first external peripheral wall 31. Thefirst partitioning walls 32 are, for example, formed so as to give asubstantially cross shaped (lattice shaped) cross-section.

Namely, the first shock absorbing member 26 is famed with a closedcross-section by the first external peripheral wall 31, and the closedcross-section is partitioned into plural small compartments (closedcross-sections) 33 in a lattice shape by the first partitioning walls32. The first shock absorbing member 26 is thus formed with a closedcross-section substantially in the shape of a rectangle divided intofour smaller rectangles.

The second shock absorbing member 27 is joined to the vehicle widthdirection outside of the first external peripheral wall 31 by welding.

Similarly to the first shock absorbing member 26, the second shockabsorbing member 27 is, for example, a member formed by extruding alightweight metal such as an aluminum alloy so as to extend with auniform cross-section profile along the vehicle body front-reardirection. The second shock absorbing member 27 can accordingly beformed (namely, manufactured) easily.

The coupling plate 25, the first shock absorbing member 26, and thesecond shock absorbing member 27 (namely, the left bumper beam extension18) can accordingly be easily manufactured.

A base portion 27 a of the second shock absorbing member 27 is joined toa vehicle width direction outside half 25 b of the coupling plate 25 byMIG welding. Specifically, the second shock absorbing member 27 includesa second external peripheral wall 34 famed with a substantially U-shapedcross-section (a shape corresponding to three sides of a rectangle), anda second partitioning wall 35 that internally partitions the secondexternal peripheral wall 34.

The second external peripheral wall 34 is formed with a substantiallyU-shaped cross-section opening toward the vehicle width directioninside. An upper inside end portion 34 a of the second externalperipheral wall 34 is joined to an upper outside end portion 31 a of thefirst external peripheral wall 31 by welding. Moreover, a lower insideend portion 34 b of the second external peripheral wall 34 is joined toa lower outside end portion 31 b of the first external peripheral wall31 by welding. In this joined state, the inside of the second externalperipheral wall 34 is divided into small compartments (closedcross-sections) 36 on the inside and the outside of the secondpartitioning wall 35. The second partitioning wall 35 is famed with asubstantially I-shaped cross-section.

A closed cross-section in the shape of a rectangle divided into twosmaller rectangles is formed by the second shock absorbing member 27 andthe first external peripheral wall 31.

A large cross-section is secured for the left bumper beam extension 18due to joining the second shock absorbing member 27 to the vehicle widthdirection outside of the first external peripheral wall 31 by welding.Specifically, an external face 38 of the left bumper beam extension 18includes an upper face 38 a, an inside face 38 b, an outside face 38 c,and a lower face 38 d. The external face 38 of the left bumper beamextension 18 is formed with an external profile with a substantiallyrectangular shaped cross-section by the upper face 38 a, the inside face38 b, the outside face 38 c, and the lower face 38 d.

A width dimension W1 of the upper face 38 a and the lower face 38 d(namely, of the left bumper beam extension 18) is formed larger than aheight dimension H1 of the inside face 38 b and the outside face 38 c(namely, of the left bumper beam extension 18). Moreover, the inside ofthe left bumper beam extension 18 is partitioned into the plural smallcompartments 33, and the inner and outer small compartments 36.

Accordingly, the left bumper beam extension 18 is secured withappropriate strength and rigidity against light collisions (namely,light frontal collisions in a low speed range in which it is notnecessary to deploy an airbag). This thereby enables compression(namely, axial crushing) of the left bumper beam extension 18 to besuppressed in a light collision.

However, for example, in a high speed frontal collision or a smalloverlap collision sufficient to fully crush the bumper beam extensionover its entire range, the left bumper beam extension 18 can beadequately compressed by the impact load.

Moreover, the front portion 15 a of the left upper member 15 is coupledto the front portion 13 a of the left front side frame 13 by the leftcoupling section 16. The left bumper beam extension 18 is provided atthe front end 13 b of the left front side frame 13 and the front end 16c of the left coupling section 16.

Accordingly, in a high speed frontal collision or a small overlapcollision, for example, impact load can be supported by both the leftfront side frame 13 and the left upper member 15.

The left bumper beam extension 18 can thus undergo adequate compression(axial crushing) due to the impact load.

In this manner, in a high speed frontal collision or a small overlapcollision, for example, the left bumper beam extension 18 is adequatelycompressed by the input impact load, thereby enabling an energyabsorption amount to be increased.

Note that a small overlap collision is a collision in which a frontsection of the vehicle collides with an obstacle such as a vehicle,tree, or electricity pole at a front side portion at the outside of theleft front side frame 13 at ¼ in the vehicle width direction. Note thatsmall overlap collisions are also referred to as narrow offsetcollisions.

As illustrated in FIG. 6, a left end portion 22 a of the bumper beam 22is joined to the front end 18 a of the left bumper beam extension 18.The bumper beam 22 is, for example, a member formed from a lightweightmetal member such as an aluminum alloy. A beam rear wall (rear portion)22 b of the left end portion 22 a of the bumper beam 22 is joined(fixed) to the front end 18 a of the left bumper beam extension 18 byMIG welding.

As illustrated in FIG. 2, a beam rear wall (rear portion) 22 d of aright end portion 22 c of the bumper beam 22 is joined (fixed) to thefront end 18 a of the right bumper beam extension 18 by MIG welding. Theleft bumper beam extension 18 accordingly extends out along the vehiclewidth direction.

In this state, a left section 22 e of the bumper beam 22 extends out atan angle toward the vehicle width direction outside and the vehicle bodyrear. Similarly, a right section 22 f of the bumper beam 22 extends outat an angle toward the vehicle width direction outside and the vehiclebody rear.

Returning to FIG. 6, the bumper beam 22 includes a beam externalperipheral wall 41 formed with a substantially rectangular shaped closedcross-section, and plural beam partitioning walls (for example, upperand lower beam partitioning walls) 42 that internally partition the beamexternal peripheral wall 41.

The beam external peripheral wall 41 includes a beam front wall 41 aprovided at a vehicle body front side, a beam rear wall 41 b provided atthe vehicle body rear of the beam front wall 41 a, a beam top portion 41c coupling an upper end portion of the beam front wall 41 a and an upperend portion of the beam rear wall 41 b together, and a beam bottomportion 41 d coupling a lower end portion of the beam front wall 41 aand a lower end portion of the beam rear wall 41 b together.

The beam front wall 41 a, the beam rear wall 41 b, the beam top portion41 c, and the beam bottom portion 41 d form the beam external peripheralwall 41 with a substantially rectangular shaped hollow cross-section.

The upper and lower beam partitioning walls 42 inside the beam externalperipheral wall 41 are provided substantially parallel to each other ata separation in the up-down direction. The beam external peripheral wall41 is thereby internally partitioned into plural small compartments 43in the up-down direction by the upper and lower beam partitioning walls42.

Namely, the bumper beam 22 is formed with a closed cross-sectionincluding the plural small compartments 43. The bumper beam 22 isthereby famed with a closed cross-section resembling stacked rectangles.

In this manner, the beam external peripheral wall 41 of the bumper beam22 is formed with a hollow closed cross-section partitioned into theplural small compartments 43 in the up-down direction by the upper andlower beam partitioning walls 42. The bumper beam 22 is formed so as tobe capable of undergoing bending and crushing deformation in a lightcollision (namely, in a low speed range in which it is not necessary todeploy the airbag).

Moreover, the beam rear wall 41 b at the left end portion 22 a of thebumper beam 22 is joined to the front end 18 a of the left bumper beamextension 18 by MIG welding. The left bumper beam extension 18 issecured with strength and rigidity against a light collision.

The bumper beam 22 is thereby capable of undergoing bending and crushingdeformation to absorb impact load in a light collision.

Returning to FIG. 3, the sensor attachment structure 20 is provided tothe outside face 38 c of the external face 38 of the left bumper beamextension 18. The sensor attachment structure 20 includes a supportsection 45 provided to the outside face 38 c of the left bumper beamextension 18, and an airbag sensor (Front Crash Sensor: FCS) 46 attachedto the support section 45.

As illustrated in FIG. 7 and FIG. 8, the support section 45 includes astay 47 provided to the outside face 38 c of the left bumper beamextension 18, and a bracket 48 provided to the stay 47.

The stay 47 includes an apex portion (top portion) 51 famed in asubstantially rectangular shape in side view, a front leg portion 52formed at a front end of the apex portion 51, a front joining portion 53formed at a vehicle width direction inside end of the front leg portion52, a rear leg portion 54 formed at a rear end of the apex portion 51,and a rear joining portion 55 formed at a vehicle width direction insideend of the rear leg portion 54.

The front leg portion 52 is bent from the front end of the apex portion51 toward the outside face 38 c of the left bumper beam extension 18.The front joining portion 53 is bent from the vehicle width directioninside end of the front leg portion 52 toward the vehicle body front soas to follow the outside face 38 c of the left bumper beam extension 18.

Moreover, the rear leg portion 54 is bent from the rear end of the apexportion 51 toward the outside face 38 c of the left bumper beamextension 18. The rear joining portion 55 is bent from the vehicle widthdirection inside end of the rear leg portion 54 toward the vehicle bodyrear so as to follow the outside face 38 c of the left bumper beamextension 18.

The apex portion 51, the front leg portion 52, the front joining portion53, the rear leg portion 54, and the rear joining portion 55 form thestay 47 with a substantially hat-shape in plan view. The stay 47 isformed from an aluminum alloy, similarly to the left bumper beamextension 18.

The front joining portion 53 is joined to a frontal location 38 e of theoutside face 38 c of the left bumper beam extension 18. The rear joiningportion 55 is joined to the outside face 38 c of the left bumper beamextension 18 at a location 38 f that is at a spacing L1 toward thevehicle body rear of the front joining portion 53 by. Namely, the frontjoining portion 53 and the rear joining portion 55 are provided to theoutside face 38 c of the left bumper beam extension 18 with the spacingL1 in the vehicle body front-rear direction.

In this state, the apex portion 51 is disposed at a position separatedtoward the vehicle width direction outside from the outside face 38 c ofthe left bumper beam extension 18.

The bracket 48 is provided to the apex portion 51 of the stay 47. Thebracket 48 is formed from sheet steel. Specifically, the bracket 48includes an attachment base portion 56 attached to the apex portion 51,a projecting portion 57 projecting out from the attachment base portion56, a flange 58 formed to the attachment base portion 56 and theprojecting portion 57, and a connector protector 59 formed to theprojecting portion 57.

The attachment base portion 56 is fastened to the apex portion 51 by abolt 61 and a nut 62 (namely, a fastening member) in an abutted state ofthe attachment base portion 56 along the apex portion 51 of the stay 47.The projecting portion 57 is bent from a front end of the attachmentbase portion 56 toward the vehicle width direction outside. Theattachment base portion 56 and the projecting portion 57 form thebracket 48 with a substantially L-shape in plan view.

Note that the stay 47 is famed from an aluminum alloy, and the bracket48 is formed from sheet steel. The attachment base portion 56 made fromsteel is thus attached to the apex portion 51 made from an aluminumalloy by the bolt 61 and the nut 62. The bolt 61 and the nut 62 arecoated against galvanic corrosion.

Galvanic corrosion between the stay 47, the bolt 61, and the nut 62 canaccordingly be suppressed, enabling the durability of the stay 47, thebolt 61, and the nut 62 to be raised.

Note that an anti-rust coating that decreases the potential differencebetween different materials is employed for the coating against galvaniccorrosion. An example of this is GEOMET720 (brand name and “GEOMET” is aregistered trademark).

The airbag sensor 46 is attached to the projecting portion 57 by a bolt63 and a nut 64. In this state, an upper end 46 b of the airbag sensor46 is disposed at the vehicle width direction inside and upper side of alower end 46 a of the airbag sensor 46.

Namely, the airbag sensor 46 is disposed in an inclined state upward andtoward the vehicle width direction inside.

The airbag sensor 46 is installed with a detector (namely a G-chip) 66inside a sensor case 65.

A wire harness 67 is connected to the upper end 46 b of the airbagsensor 46. The wire harness 67 extends from the upper end 46 b of theairbag sensor 46 in an inclined state upward and toward the vehiclewidth direction inside.

The attachment base portion 56 and the projecting portion 57 are formedin a substantially L-shape in plan view, thus foaming a bend portion 68at a location where the attachment base portion 56 and the projectingportion 57 intersect each other. The flange 58 is formed so as to becontinuous to respective lower ends (namely, lower ends of the bracket48) 48 a of the attachment base portion 56, the projecting portion 57,and the bend portion.

Specifically, the flange 58 includes a first flange location 58 a bentfrom the lower end of the attachment base portion 56 toward the vehiclewidth direction outside, a second flange location 58 b bent from thelower end of the projecting portion 57 toward the vehicle body rear, anda third flange location 58 c bent from the lower end of the bend portionso as to couple the first flange location 58 a and the second flangelocation 58 b together.

The flange 58 is famed at the lower ends 48 a of the bracket 48 in thismanner. The strength and rigidity of the bracket 48 can accordingly beraised by the flange 58. This thereby enables the characteristicresonance value of the bracket 48 to be raised, and enables theanti-noise performance (anti-vibration performance) of the airbag sensor46 to be improved.

The connector protector 59 protrudes out from an upper end 48 b(specifically, an upper end 57 a of the projecting portion 57) of thebracket 48. The connector protector 59 is disposed at the vehicle bodyfront side of the wire harness 67, and protrudes out in an inclinedstate upward and toward the vehicle width direction inside, followingthe wire harness 67.

This thereby enables the wire harness 67 of the airbag sensor 46 to beprotected by the connector protector 59, even when the airbag sensor 46is provided in a range intruded into by a colliding object. This therebyenables cutting of the connection of the wire harness 67 to the airbagsensor 46 to be prevented, even in, for example, a high speed frontalcollision, a small overlap collision, or an offset collision.

As described above, the stay 47 of the support section 45 is famed in asubstantially hat-shape in plan view, and the front joining portion 53and the rear joining portion 55 of the stay 47 are provided to theoutside face 38 c of the left bumper beam extension 18. This therebyenables the strength and rigidity of the stay 47 to be raised.

Moreover, since the stay 47 is formed in a substantially hat-shape inplan view, the apex portion 51 of the stay 47 can be separated from theoutside face 38 c of the left bumper beam extension 18.

The attachment base portion 56 of the bracket 48 is provided at the apexportion 51 of the stay 47, and the projecting portion 57 projects outfrom the attachment base portion 56. The projection amount (extensionamount) of the projecting portion 57 can thereby kept small. The airbagsensor 46 is attached to the projecting portion 57.

The characteristic vibration value of the support section 45 is therebyraised in a state in which the airbag sensor 46 is supported by thesupport section 45, enabling the anti-noise performance (anti-vibrationperformance) of the airbag sensor 46 to be improved. This therebyenables collision information required for airbag deployment to bedetected precisely and at an early stage by the airbag sensor 46.

Note that it is conceivable that, for example, the bracket 48 (namely,the projecting portion 57) could hit a counterpart vehicle in an offsetcollision at a lower limit of a speed for actuating the airbag(specifically, in an intermediate speed range).

The bracket 48 is therefore formed from sheet steel. This therebyenables a bending state of the projecting portion 57 with respect toimpact load input to the projecting portion 57 to be regulated(controlled) easily when the projecting portion 57 of the bracket 48hits the counterpart vehicle.

Returning to FIG. 4, the support section 45 is provided to the outsideface 38 c of the left bumper beam extension 18, and the airbag sensor 46is attached to the support section 45.

Note that, for example in a light collision in a low speed range inwhich it is not necessary to deploy the airbag, the bumper beam 22undergoes bending and crushing deformation to absorb the impact load. Onthe other hand, the left bumper beam extension 18 has sufficientstrength and rigidity against light collisions. There is accordinglylittle compression (namely, axial compression) of the left bumper beamextension 18 in a light collision.

Movement of the airbag sensor 46 toward the vehicle body rear in a lightcollision is thereby suppressed, enabling the airbag sensor 46 to beprevented from making unnecessary detection of a light collision anddeploying the airbag.

Note that in an offset collision at the lower limit of the speed foractuating the airbag, the front end 18 a of the left bumper beamextension 18 intrudes into a comparatively soft location of a frontmostsection of the counterpart vehicle in an initial stage of the offsetcollision. Accordingly, the comparatively soft location of thecounterpart vehicle impinges on the support section 45 (in particular,the projecting portion 57), such that the projecting portion 57 is benttoward the vehicle body rear, and the support section 45 retreats towardthe vehicle body rear.

The airbag sensor 46 accordingly retreats toward the vehicle body reartogether with the support section 45, enabling collision informationrequired for airbag deployment to be detected precisely and at an earlystage by the airbag sensor 46. This thereby enables the airbag to bedeployed in an initial stage of the offset collision.

Note that an offset collision is a collision in which part of the frontsection of the vehicle (approximately half of the width of the front ofthe vehicle body) collides with an obstacle such as another vehicle.

Moreover, the front joining portion 53 and the rear joining portion 55of the stay 47 are provided to the outside face 38 c of the left bumperbeam extension 18 at the spacing L1 in the vehicle body front-reardirection. Namely, the strength and rigidity of the stay 47 in thedirection in which the left bumper beam extension 18 is compressed arekept appropriately low.

Accordingly, in a high speed frontal collision or a small overlapcollision sufficient to fully crush the left bumper beam extension 18over its entire range, the front joining portion 53 of the stay 47 canbe moved appropriately toward the vehicle body rear during compressionof the left bumper beam extension 18 toward the vehicle body rear due tothe input impact load.

Since the front joining portion 53 of the stay 47 is moved appropriatelytoward the vehicle body rear, there is no concern of compression(crushing defamation) of the left bumper beam extension 18 beingobstructed by the stay 47. This thereby enables stable compression ofthe left bumper beam extension 18 toward the vehicle body rear, andenables stable defamation of the left front side frame 13.

Accordingly, the airbag sensor 46 can be made to retreat appropriatelytoward the vehicle body rear due to compression of the left bumper beamextension 18. This thereby enables collision information for a highspeed frontal collision or small overlap collision to be detectedprecisely and at an early stage by the airbag sensor 46.

As illustrated in FIG. 9, the airbag sensor 46 on the left side isattached to the left bumper beam extension 18 through the supportsection 45 on the left side. The airbag sensor 46 on the right side isattached to the right bumper beam extension 18 through the supportsection 45 on the right side. The left side airbag sensor 46 and theright side airbag sensor 46 are similar members.

Note that, for example, if the left side airbag sensor 46 and the rightside airbag sensor 46 were disposed vertically, the detector 66 of theleft side airbag sensor 46 would be disposed on the vehicle widthdirection outside of the bolt 63. On the other hand, the detector 66 ofthe right side airbag sensor 46 would be disposed on the vehicle widthdirection inside of the bolt 63.

Accordingly, the detector 66 on the left side would be a greaterdistance from a vehicle body center 72 than the detector 66 on the rightside. Accordingly, for example, were the vehicle body front sectionstructure 10 to be involved in a high speed frontal collision, aleft/right discrepancy would arise between the left side detector 66 andthe right side detector 66, making accurate collision mode determinationdifficult.

The left side airbag sensor 46 is therefore attached in a state inclinedupward toward the vehicle width direction inside. The left side detector66 of the left side airbag sensor 46 is thereby disposed further to thevehicle width direction inside than it would be if installed vertically,as shown by arrow A.

However, the right side airbag sensor 46 is attached in a state inclinedupward toward the vehicle width direction inside. The right sidedetector 66 of the right side airbag sensor 46 is thereby disposedfurther to the vehicle width direction outside than it would be ifinstalled vertically, as shown by arrow B.

Namely, a distance L2 from the left side detector 66 to the vehicle bodycenter 72 can be made the same as a distance L3 from the right sidedetector 66 to the vehicle body center 72. Accordingly, for example, adiscrepancy in detection between the left side detector 66 and the rightside detector 66 can be suppressed from arising when the vehicle bodyfront section structure 10 is involved in a high speed frontalcollision.

This thereby enables the left side airbag sensor 46 and the right sideairbag sensor 46 to accurately determine the collision mode of a highspeed frontal collision.

Moreover, the left side airbag sensor 46 attached to the left bumperbeam extension 18 and the right side airbag sensor 46 attached to theright bumper beam extension 18 are configured by similar members.

In this manner, the left side airbag sensor 46 and the right side airbagsensor 46 can be configured using common components, thereby enablingthe cost of the sensor attachment structure 20 to be suppressed.

Moreover, the left side airbag sensor 46 and the right side airbagsensor 46 are inclined, and the upper ends 46 b of the respective airbagsensors 46 approach the sides of the respective stays 47, respectively.This thereby enables the wire harness 67 connected to the upper end 46 bof the left side airbag sensor 46 to be brought closer to the side ofthe left side stay 47.

Similarly, the wire harness 67 connected to the upper end 46 b of theright side airbag sensor 46 can be brought closer to the side of theright side stay 47.

This thereby enables the connector protector 59 that protects the leftside wire harness 67 to be brought closer to the left side stay 47,enabling the characteristic vibration value of the left side supportsection 45 to be raised. Similarly, the connector protector 59 thatprotects the right side wire harness 67 can be brought closer to theright side stay 47, enabling the characteristic vibration value of theright side support section 45 to be raised.

Accordingly, resonance of the left and right side airbag sensors 46 issuppressed, thereby enabling erroneous detection by the left and rightside airbag sensors 46 to be even better prevented.

Moreover, the left side airbag sensor 46 is inclined, thereby enabling aheight H2 of the left side airbag sensor 46 to be kept low. Similarly,the right side airbag sensor 46 is inclined, thereby enabling a heightH3 of the right side airbag sensor 46 to be kept low. This therebyenables a space 74 to be secured above the left side airbag sensor 46,and enables a space 75 to be secured above the right side airbag sensor46.

This enables an increase in the degree of freedom in the layout ofsurrounding components when placing surrounding components (headlights,cooling pipes, and small lights such as fog lamps) in the space 74 andthe space 75. This moreover enables any effect on the performance of thesurrounding components to be kept small.

Next, with reference to FIG. 10A and FIG. 10B, explanation followsregarding an example of absorption of an input impact load F1 by thevehicle body front section structure 10 when the impact load F1 is inputto the vehicle body front section structure 10 in a light collision(namely, in a low speed range in which it is not necessary to deploy theairbag).

As illustrated in FIG. 10A, in a light collision, the impact load F1 isinput into the bumper beam 22 of the vehicle body front sectionstructure 10.

Note that the width dimension W1 of the left bumper beam extension 18 isformed large, and the inside of the left bumper beam extension 18 ispartitioned into the plural small compartments 33 and the inner andouter small compartments 36 (see FIG. 5). Similarly, the width dimensionW1 of the right bumper beam extension 18 is formed large, and the insideof the right bumper beam extension 18 is partitioned into plural smallcompartments and inner and outer small compartments.

Accordingly, the left bumper beam extension 18 and the right bumper beamextension 18 are secured with appropriate strength and rigidity againstthe impact load F1 input to the bumper beam 22.

As illustrated in FIG. 10B, the bumper beam 22 undergoes bending andcrushing defamation due to the impact load F1 input to the bumper beam22. Moreover, a leading end portion 18 c of the left bumper beamextension 18 and a leading end portion 18 c of the right bumper beamextension 18 also deform.

The impact load F1 input in a light collision can be absorbed by thedeformation of the bumper beam 22 and of the respective leading endportions 18 c of the left bumper beam extension 18 and the right bumperbeam extension 18.

Accordingly, the left bumper beam extension 18 and the right bumper beamextension 18 can be suppressed from undergoing compression (namely,axial crushing) toward the vehicle body rear. This thereby enables theleft side airbag sensor 46 and the right side airbag sensor 46 to bemaintained in a static state, thereby enabling the left and right airbagsensors 46 to be prevented from unnecessarily detecting a lightcollision and deploying the airbag.

Next, with reference to FIG. 11A and FIG. 11B, explanation followsregarding an example in which the airbag is deployed due to an inputimpact load F2 when the impact load F2 is input to the vehicle bodyfront section structure 10 in an offset collision at the lower limit ofthe speed for actuating the airbag (specifically, in the intermediatespeed range).

Note that FIG. 11B illustrates the left side members and omits the rightside members in order to facilitate understanding of the operation.

As illustrated in FIG. 11A, in an offset collision the impact load F2 isinput to the bumper beam 22 of the vehicle body front section structure10. The bumper beam 22 undergoes bending and crushing defamation due tothe impact load F2 input to the bumper beam 22. Moreover, the leadingend portion 18 c of the left bumper beam extension 18 and the leadingend portion 18 c of the right bumper beam extension 18 also deform.

As illustrated in FIG. 11B, in an initial stage of the offset collision,the front end 18 a of the left bumper beam extension 18 intrudes into acomparatively soft location 82 a of a frontmost section of a counterpartvehicle 82, as illustrated by arrow C.

Accordingly, the comparatively soft location 82 a of the counterpartvehicle impinges on the support section 45 (in particular, theprojecting portion 57). The projecting portion 57 bends toward thevehicle body rear, and the airbag sensor 46 retreats toward the vehiclebody rear together with the support section 45, as illustrated by arrowD.

The airbag sensor 46 accordingly retreats toward the vehicle body reartogether with the support section 45, as illustrated by arrow D. Thecollision information required for airbag deployment can accordingly bedetected precisely and at an early stage by the airbag sensor 46 due tothe airbag sensor 46 retreating.

This thereby enables the airbag to be deployed in an initial stage ofthe offset collision.

Next, with reference to FIG. 12A, FIG. 12B, and FIG. 13, explanationfollows regarding an example in which the airbag is deployed due to animpact load F3 input when the impact load F3 is input in a high speedfrontal collision to the vehicle body front section structure 10(namely, in a high speed region sufficient to fully crush the leftbumper beam extension 18 or the right bumper beam extension 18 over itsentire range).

Note that FIG. 13 illustrates the left side members and omits the rightside members in order to facilitate understanding of the operation.

As illustrated in FIG. 12A, the impact load F3 is input to the bumperbeam 22 of the vehicle body front section structure 10 by the high speedfrontal collision. The bumper beam 22 undergoes bending and crushingdeformation due to the impact load F3 being input to the bumper beam 22.Moreover, the leading end portion 18 c of the left bumper beam extension18 and the leading end portion 18 c of the right bumper beam extension18 also deform.

As illustrated in FIG. 12B, the front portion 15 a of the left uppermember 15 is coupled to the front portion 13 a of the left front sideframe 13 by the left coupling section 16. Moreover, the left bumper beamextension 18 is provided at the front end 13 b of the left front sideframe 13 and at the front end 16 c of the left coupling section 16.

Accordingly, the impact load F3 can be supported by both the left frontside frame 13 and the left upper member 15 in a high speed frontalcollision. This thereby enables the entire region of the left bumperbeam extension 18 to undergo sufficient compression (namely, axialcrushing) toward the vehicle body rear due to the impact load F3, asillustrated by arrow E.

As illustrated in FIG. 13, the front joining portion 53 and the rearjoining portion 55 of the stay 47 are provided to the outside face 38 cof the left bumper beam extension 18 at the spacing L1 in the vehiclebody front-rear direction. Accordingly, the front joining portion 53 ofthe stay 47 can be moved toward the vehicle body rear, as illustrated byarrow E, when the left bumper beam extension 18 is compressed toward thevehicle body rear in a high speed frontal collision, as illustrated byarrow E.

Accordingly, there is no concern of compression (crushing defamation) ofthe left bumper beam extension 18 being obstructed by the stay 47. Thisthereby enables stable compression of the left bumper beam extension 18toward the vehicle body rear as illustrated by arrow E, and enablesstable defamation of the left front side frame 13.

In this manner, the entire range of the left bumper beam extension 18 issufficiently compressed by the impact load F3, thereby enabling asufficient energy absorption amount with respect to the impact load F3to be secured.

Note that during compression of the left bumper beam extension 18, thesupport section 45 (specifically, the stay 47 and the bracket 48) can bedeformed toward the vehicle body rear in response to this compression,as illustrated by arrow E. This thereby enables the airbag sensor 46 tobe made to retreat toward the vehicle body rear together with thebracket 48, as illustrated by the arrow E.

This thereby enables collision information of the high speed frontalcollision to be detected precisely and at an early stage by the airbagsensor 46. This thereby enables the airbag to be deployed in an initialstage of the high speed frontal collision.

Note that similarly to in a high speed frontal collision, in a smalloverlap collision sufficient to fully crush the left bumper beamextension 18 over its entire range, impact load can be supported by boththe left front side frame 13 and the left upper member 15. Moreover, thefront joining portion 53 of the stay 47 can be moved toward the vehiclebody rear by the impact load.

Accordingly, the left bumper beam extension 18 can be sufficientlycompressed over its entire range by the impact load, thereby enabling asufficient energy absorption amount with respect to the impact load tobe secured.

The airbag sensor 46 can be made to retreat toward the vehicle body rearsince the left bumper beam extension 18 is sufficiently compressed bythe impact load. Similarly to in a high speed frontal collision, thisenables collision information to be detected precisely and at an earlystage by the airbag sensor 46 in a small overlap collision, enabling theairbag to be deployed in an initial stage of the collision.

Note that the airbag sensor attachment structure according to thepresent disclosure is not limited to the above embodiment, and may bemodified and improved on as appropriate.

For example, in the above embodiment, explanation has been givenregarding an example in which the coupling plate 25, the first shockabsorbing member 26, and the second shock absorbing member 27 arelightweight metal members configured by an aluminum alloy or the like.However, there is no limitation thereto.

For example, the coupling plate 25, the first shock absorbing member 26,and the second shock absorbing member 27 may be formed from sheet steel.In such a configuration, the coupling plate 25 and the left couplingsection 16 are joined together by MIG welding, and the coupling plate 25and the second shock absorbing member 27 are joined together by MIGwelding.

Moreover, in the above embodiment, explanation has been given regardingan example in which the sensor attachment structure 20 is provided tothe outside face 38 c of the external face 38 of the left bumper beamextension 18. However, there is no limitation thereto. For example, thesensor attachment structure 20 may be provided to the upper face 38 a,the inside face 38 b, or the lower face 38 d of the external face 38 ofthe left bumper beam extension 18.

Moreover, in the above embodiment, explanation has been given regardingan example in which the attachment base portion 56 of the bracket 48 isattached to the apex portion 51 of the stay 47 by the bolt 61 and thenut 62. However, there is no limitation thereto, and attachment may beperformed using other fastening members, such as rivets.

Moreover, in the above embodiment, explanation has been given regardingan example in which the flange 58 is formed so as to be continuous tothe lower ends 48 a of the bracket 48. However, there is no limitationthereto, and a flange may be formed so as to be continuous to the upperend 48 b of the bracket 48.

Moreover, in the above embodiment, explanation has been given regardingan example in which the connector protector 59 protrudes out from theupper end 57 a of the projecting portion 57; however, there is nolimitation thereto. For example, in a configuration in which the wireharness 67 extends downward from the airbag sensor 46, the connectorprotector 59 may protrude out from a lower end of the projecting portion57 so as to follow the wire harness 67.

Moreover, there is no limitation to the shapes and configurations of thevehicle body front section structure, the vehicle body, the left andright front side frames, the left and right upper members, the left andright coupling sections, the left and right bumper beam extensions, thesensor attachment structure, the bumper beam, the beam rear wall, theairbag sensor, the stay, the bracket, the apex portion, the frontjoining portion, the rear joining portion, the attachment base portion,the projecting portion, the flange, the connector protector, or the bendportion. These may be modified as appropriate.

The present disclosure is preferably applied to an automobile providedwith an airbag sensor attachment structure in which an airbag sensor isattached at the vehicle body front of a front side frame. Although aspecific form of embodiment has been described above and illustrated inthe accompanying drawings in order to be more clearly understood, theabove description is made by way of example and not as limiting thescope of the invention defined by the accompanying claims. The scope ofthe invention is to be determined by the accompanying claims. Variousmodifications apparent to one of ordinary skill in the art could be madewithout departing from the scope of the invention. The accompanyingclaims cover such modifications.

We claim:
 1. An airbag sensor attachment structure for attachment to avehicle body front section structure comprising a front side frameextending in a vehicle body front-rear direction and a bumper beamextension extending out from a front end of the front side frame towardthe vehicle body front at respective front side sections of a vehiclebody, and a bumper beam provided at a front end of the bumper beamextension, the airbag sensor attachment structure comprising: a supportmember that is provided to an external face of the bumper beamextension, and that moves toward the vehicle body rear in accordancewith compression of the bumper beam extension during compression of thebumper beam extension due to an impact load input from the vehicle bodyfront; and an airbag sensor that is attached to the support member. 2.The airbag sensor attachment structure of claim 1, wherein the supportmember includes: a stay that includes a front joining portion and a rearjoining portion provided on the external face of the bumper beamextension, and a substantially u-shape portion connected to andprotruding from the front joining portion and the rear joining portion,the front joining portion, the rear joining portion and thesubstantially u-shape portion makes a substantially hat-shape in planview; and a bracket that includes an attachment base portion provided toa top portion of the substantially u-shape portion of the stay, the topportion being separated away from the external face of the bumper beamextension, and a projecting portion projecting from the attachment baseportion and to which the airbag sensor is attached, wherein theprojecting portion and the attachment base portion makes a substantiallyL-shape in plan view.
 3. The airbag sensor attachment structure of claim2, wherein the bracket is formed by plate steel.
 4. The airbag sensorattachment structure of claim 3, wherein: the bumper beam extension andthe stay are formed by an aluminum alloy; the bracket is fastened to thestay by a fastening member; and the fastening member is coated withgalvanic corrosion resistant coating.
 5. The airbag sensor attachmentstructure of claim 1, wherein: the bumper beam has a hollowcross-section, and a rear portion at respective longitudinal endportions of the bumper beam is fixed to the front end of the bumper beamextension; and the bumper beam extension has strength and rigidityagainst a light collision.
 6. The airbag sensor attachment structure ofclaim 2, wherein: the bumper beam has a hollow cross-section, and a rearportion at respective longitudinal end portions of the bumper beam isfixed to the front end of the bumper beam extension; the bumper beamextension has rigidity against a light collision; and the front joiningportion and the rear joining portion of the stay are provided on theexternal face of the bumper beam extension with a space therebetween inthe vehicle body front-rear direction.
 7. The airbag sensor attachmentstructure of claim 2, wherein the bracket includes: a flange that isdisposed at an upper end or a lower end of the bracket so as to becontinuous to the attachment base portion, the projecting portion, and abend portion where the attachment base portion and the projectingportion intersect; and a connector protector that protrudes out from theupper end or the lower end of the bracket.
 8. The airbag sensorattachment structure of claim 1, wherein: a left side airbag sensor ofthe airbag sensor is attached to a left side bumper beam extension ofthe bumper beam extension, and a right side airbag sensor of the airbagsensor is attached to a right side bumper beam extension of the bumperbeam extension; and the left side airbag sensor and the right sideairbag sensor are inclined such that a distance from the left sideairbag sensor to a vehicle body center, and a distance from the rightside airbag sensor to the vehicle body center, are equal to each other.9. The airbag sensor attachment structure of claim 1, wherein the bumperbeam extension has a substantially rectangular shaped externalcross-section, has a width dimension larger than a height dimension, andis internally partitioned into a plurality of closed cross-sections. 10.The airbag sensor attachment structure of claim 1, further comprising:an upper member provided on a vehicle width direction outside of thefront side frame; and a coupling section that couples a front portion ofthe upper member and a front portion of the front side frame together,wherein the bumper beam extension is provided at the front end of thefront side frame and at a front end of the coupling section.
 11. Theairbag sensor attachment structure of claim 1, wherein the externalsurface of the bumper beam extension is an external surface extending inthe vehicle body front-rear direction.
 12. The airbag sensor attachmentstructure of claim 11, wherein the external surface of the bumper beamextension is an outer side face in a vehicle width direction.
 13. Theairbag sensor attachment structure of claim 2, wherein the substantiallyu-shape portion protrudes in a vehicle width direction, and theprojecting portion of the bracket projects in the vehicle widthdirection.
 14. The airbag sensor attachment structure of claim 13,wherein the projecting portion is disposed at a front end of theattachment base portion with a bending portion therebetween.
 15. Theairbag sensor attachment structure of claim 14, wherein the projectingportion has a plate shape including a rear surface facing the vehiclebody rear, and the airbag sensor is attached to the rear surface. 16.The airbag sensor attachment structure of claim 8, wherein the left sideairbag sensor and the right side airbag sensor are inclined toward thevehicle body center.
 17. The airbag sensor attachment structure of claim9, wherein the bumper beam extension is partitioned by a partitionextending in the vehicle body front-rear direction.
 18. A vehiclecomprising the airbag sensor attachment structure of claim 1.